Liquid manure systems are commonly used in livestock operations. In the conventional liquid manure system, the manure is flushed from the barn or feeding area and delivered to a below-ground pit, and the manure slurry is subsequently pumped from the pit into a mobile tank for spreading on the fields. Before pumping the slurry from the pit, the slurry is agitated in order to break up the solid materials and provide a more homogeneous mass.
In the conventional liquid manure system, a chopper pump is used to agitate and chop the fibrous materials in the slurry and subsequently to pump the slurry from the pit. The conventional chopper pump includes a pump housing having a bottom inlet and a tangential outlet and the outlet of the pump is connnected to an adjustable nozzle which can be moved to agitate the slurry. After agitation, the outlet of the pump is connected to a delivery pipe to pump the slurry to a discharge site or mobile tank.
In the typical chopper pump, a chopper blade is formed integrally with the impeller and rotates in close proximity to a series of fixed chopper teeth carried by a chopper plate bordering the inlet opening to thereby chop or comminute the particulate material in the manure slurry. After a period of use, the chopper blade will wear, and in the past, due to the integral construction, it has been necessary to replace the entire impeller in order to obtain a new chopper blade.
As the manure slurry contains fibrous or stringy materials, as well as solid materials, there is a tendency for the fibrous material to wind up on the rotating impeller and clog the pump. In an attempt to prevent this problem, slingers or blades have been attached to an extension of the impeller shaft and have been located below the inlet to the pump. Rotation of the blade or slinger acts to cut the stringy fibrous material, but it has been found that the stringy material will nevertheless, tend to wind around the shaft of the blade to thereby restrict the intake opening to the pump and ultimately cause clogging of the pump.